Study On Turbulent Flow And Heat Transfer In Internal Cooling Passage With Helix-alike Fins

There is a growing tendency that the temperature at the inlet of gas turbine becomes higher and higher to achieve higher thermal efficiency and higher power density. This tendency makes the lifetime expectancy of blade reduced significantly. Consequently, the turbine blades which are the key component of gas turbine must be cooled in order to operate in an environment of high gas temperature and to extend their durability. The efficient and advanced cooling technology of the gas turbine blades is one of the most active territory of technical research and academic interest, which also is the key technology to develop more efficient and advanced gas turbine. Based on the study of the great deals of domestic and foreign references concerned gas turbine blades cooling technology, including several basic cooling technology, such as film cooling, impinging cooling and forced convective cooling, especially the internal cooling passage with fins, this thesis presents a newly proposed scheme of internal cooling passage of gas turbine blade, in which the mechanism of fored convection in spiral finned-tube is introduced into the internal cooling passage to obtain more uniformity of temperature distribution and high overall enhancement of heat transfer between the solid faces and cooling air and to lower the temperature of turbine blade surfaces by rearranging the fins geometrical parameters and their space collocation in the internal cooling passage.In this thesis, numerical simulation is employed together with experimental investigation to study the special characteristic of 3-D turbulent flow field, heat transfer coefficient distribution and average duct pressure loss in the newly proposed internal cooling channel with helix-alike fins. In this novel heat transfer augmentation scheme of internal cooling passage of the gas turbine blades, several staggered arrays of discrete helix-alike fins with a certain angle are used on the up and down inside walls of the internal cooling passage. These arrays of fins are mounted periodically along the main streamwise, and two arrays of fins are one periodicity unit of the geometric structure in the cooling dcut. Meanwhile, both the running-lengthwise arrays of helix-alike fins on the same wall and the face to face arrays on the up and down inside walls are staggered with definite distance.The cross-section of the internal cooling passage is rectangular, and the two side walls of the internal cooling passage are smooth. The detailed discussion and anlysis of the influences of some geometrical and fluid flow parameters on the fluid flow characteristic, heat transfer enhancement and pressure drop in the internal cooling passage with helix-alike fins is presented in this thesis. These...